BYR Achieve · 镜像论坛

在上一期热点文献推荐中，我们为您推荐了AI大语言模型的最新进展，包括：来自Google DeepMind的研究团队提出的新方法FunSearch——利用大语言模型的程序搜索解决数学难题、基于大语言模型的科学文本结构化信息提取、大语言模型简化临床研究机器学习、利用大语言模型预测化学。本期我们为您选取了4篇文献，介绍集成电路的最新进展，包括：集成调频光参量振荡器、使用单个激光器的片上全光分频、基于光子芯片的低噪声微波振荡器、用于微波和毫米波生成的集成光学分频。文献一集成调频光参量振荡器 Integrated frequency-modulated optical parametric oscillator Stokowski, Hubert S., etc. NATURE, 2024, 627(8002): 95–100 Optical frequency combs have revolutionized precision measurement, time-keeping and molecular spectroscopy. A substantial effort has developed around ‘microcombs’: integrating comb-generating technologies into compact photonic platforms. Current approaches for generating these microcombs involve either the electro-optic or Kerr mechanisms. Despite rapid progress, maintaining high efficiency and wide bandwidth remains challenging. Here we introduce a previously unknown class of microcomb—an integrated device that combines electro-optics and parametric amplification to yield a frequency-modulated optical parametric oscillator (FM-OPO). In contrast to the other solutions, it does not form pulses but maintains operational simplicity and highly efficient pump power use with an output resembling a frequency-modulated laser. We outline the working principles of our device and demonstrate it by fabricating the complete optical system in thin-film lithium niobate. We measure pump-to-comb internal conversion efficiency exceeding 93% (34% out-coupled) over a nearly flat-top spectral distribution spanning about 200 modes (over 1 THz). Compared with an electro-optic comb, the cavity dispersion rather than loss determines the FM-OPO bandwidth, enabling broadband combs with a smaller radio-frequency modulation power. The FM-OPO microcomb offers robust operational dynamics, high efficiency and broad bandwidth, promising compact precision tools for metrology, spectroscopy, telecommunications, sensing and computing. 阅读原文：https://www.nature.com/articles/s41586-024-07071-2 The FM-OPO device All-optical frequency division on-chip using a single laser Zhao, Yun, etc. NATURE, 2024, 627(8004): 546–552 The generation of spectrally pure microwave signals is a critical functionality in fundamental and applied sciences, including metrology and communications. Optical frequency combs enable the powerful technique of optical frequency division (OFD) to produce microwave oscillations of the highest quality. Current implementations of OFD require multiple lasers, with space- and energy-consuming optical stabilization and electronic feedback components, resulting in device footprints incompatible with integration into a compact and robust photonic platform. Here we demonstrate all-optical OFD on a photonic chip by synchronizing two distinct dynamical states of Kerr microresonators pumped by a single continuous-wave laser. The inherent stability of the terahertz beat frequency between the signal and idler fields of an optical parametric oscillator is transferred to a microwave frequency of a Kerr soliton comb, and synchronization is achieved via a coupling waveguide without the need for electronic locking. OFD factors of N = 34 and 468 are achieved for 227 GHz and 16 GHz soliton combs, respectively. In particular, OFD enables a 46 dB phase-noise reduction for the 16 GHz soliton comb, resulting in the lowest microwave noise observed in an integrated photonics platform. Our work represents a simple, effective approach for performing OFD and provides a pathway towards chip-scale devices that can generate microwave frequencies comparable to the purest tones produced in metrological laboratories. 阅读原文：https://www.nature.com/articles/s41586-024-07136-2 Schematic of on-chip low-noise microwave generation via frequency division Photonic chip-based low-noise microwave oscillator Kudelin, Igor, etc. NATURE, 2024, 627(8004): 534–539 Numerous modern technologies are reliant on the low-phase noise and exquisite timing stability of microwave signals. Substantial progress has been made in the field of microwave photonics, whereby low-noise microwave signals are generated by the down-conversion of ultrastable optical references using a frequency comb. Such systems, however, are constructed with bulk or fibre optics and are difficult to further reduce in size and power consumption. In this work we address this challenge by leveraging advances in integrated photonics to demonstrate low-noise microwave generation via two-point optical frequency division. Narrow-linewidth self-injection-locked integrated lasers are stabilized to a miniature Fabry–Pérot cavity, and the frequency gap between the lasers is divided with an efficient dark soliton frequency comb. The stabilized output of the microcomb is photodetected to produce a microwave signal at 20 GHz with phase noise of -96 dBc Hz-1 at 100 Hz offset frequency that decreases to -135 dBc Hz-1 at 10 kHz offset—values that are unprecedented for an integrated photonic system. All photonic components can be heterogeneously integrated on a single chip, providing a significant advance for the application of photonics to high-precision navigation, communication and timing systems. 阅读原文：https://www.nature.com/articles/s41586-024-07058-z Concept of 2P-OFD for low-noise microwave generation Integrated optical frequency division for microwave and mmWave generation Sun, Shuman, etc. NATURE, 2024, 627(8004): 540–545 The generation of ultra-low-noise microwave and mmWave in miniaturized, chip-based platforms can transform communication, radar and sensing systems. Optical frequency division that leverages optical references and optical frequency combs has emerged as a powerful technique to generate microwaves with superior spectral purity than any other approaches. Here we demonstrate a miniaturized optical frequency division system that can potentially transfer the approach to a complementary metal-oxide-semiconductor-compatible integrated photonic platform. Phase stability is provided by a large mode volume, planar-waveguide-based optical reference coil cavity and is divided down from optical to mmWave frequency by using soliton microcombs generated in a waveguide-coupled microresonator. Besides achieving record-low phase noise for integrated photonic mmWave oscillators, these devices can be heterogeneously integrated with semiconductor lasers, amplifiers and photodiodes, holding the potential of large-volume, low-cost manufacturing for fundamental and mass-market applications. 阅读原文：https://www.nature.com/articles/s41586-024-07057-0 Conceptual illustration of integrated OFD “前沿文献专题推荐服务”是图书馆情报服务部学科服务的重要内容。欢迎有相关需求的科研人员与我们联系，我们将为您提供更有针对性的定题服务。联系电话：62281933 62283502 地址：西土城校区图书馆125室，沙河校区图书馆东205室联系人：杨老师闫老师邮箱：yandong80@bupt.edu.cn

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